U.S. space station delivery on tap after 8-month stoppage

An unmanned Atlas V rocket sits on the launch pad, Wednesday, Dec. 2, 2015, at Cape Canaveral, Fla.

A United Launch Alliance Atlas V 401 will launch the Orbital ATK’s Cygnus spacecraft on the initial leg of its cargo resupply mission to the International Space Station (ISS).

The primary constraints involved with this decision were thick clouds with freezing temperatures and precipitation that violated the weather rules for launching. However, as the afternoon progressed, the local weather deteriorated to the point where it violated safety guidelines and the launch was postponed. Liftoff’s expected at 5:55 p.m. ET. Launch of the Atlas V is scheduled for Thursday evening. NASA reset the launch time to 6:25 p.m. and scrubbed it just before 6:15 p.m. At the moment, forecasters are predicting only a 30% chance of good weather.

While NASA’s worldwide partners have helped keep supplies flowing to astronauts aboard the station, this will be the first U.S.-based attempt since then.

More attention than usual is focused on the Orbital CRS-4 mission because of three recent failures involving resupply efforts.

Should the spacecraft take flight on Friday, the ISS will receive about 7,300 pounds of supplies including; experiments, food, and other necessities for astronauts.

Orbital’s Antares rocket also exploded past year during its launch, which was carrying 5,000 pounds of cargo. A Russian supply run planned for later this month, if successful, would buy more time.

NASA’s other space station supply launcher, SpaceX, has been grounded since its Falcon 9 rocket broke apart several minutes after a launch this summer.

Orbital ATK plans to resume operations of its Antares rocket in 2016.

Orbital ATK’s return to flight was delayed by a rainstorm Thursday.

According to NASA, the enhanced Cygnus will carry about 3,500 kilograms of cargo to the ISS, one third of which are crew supplies.

Saturday also is a possibility, but United Launch Alliance still does not have full clearance that the range – the area beneath the rocket’s early path – will be clear and available.